One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A way of making a decision about when you can plant bok choi is to consult the USDA zone info for Washington.

Planting Calendar for Bok Choi

Frost tolerance for bok choi:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Bok Choi are one of those plants that can tolerate a little bit of cold weather which means that you can start planting them earlier than more sensitive plants.

The earliest that you can plant bok choi in Washington is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant bok choi and expect a good harvest is probably September. If you wait any later than that and your bok choi may not have a chance to fully mature. If you are starting your bok choi indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Washington. In the coldest months of winter you should expect an average low temperature of -10°F.

Since the USDA zone info for Washington may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Washington you get surprised by a frost after April 15 so always be ready to protect your bok choi in the event of a late frost.

USDA Zone Info for Washington

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Washington

You may be interested in your other planting guides for Washington.